GitLab

Removed all other manual test files in the ../webrtc/manual folder. They
too have moved to GitHub but are not used that often hence no redirect
pages are necessary.

The ../webrtc/manual folder now resides here:
https://github.com/GoogleChrome/webrtc/tree/master/samples/web/content/manual-test

BUG=NONE
NOTRY=TRUE

Review URL: https://codereview.chromium.org/609733002

Cr-Commit-Position: refs/heads/master@{#297156}